Electric switching devices



OC- 15, 1957 s. D. vlGREN ETAL 2,810,026

ELECTRIC SWITCHING DEVICES Filed Dec. 2, 1955 hum p nited States atent @thee 2,810,026 Patented Oct. 15, 1957 ELECTRIC SWITCHING DEVICES Sten Daniel Vigren, Stockholm, Walter Otto Wilhelm Broberg, Nynashamn, and Rolf Albin Zander, Stockholm, Sweden Application December 2, 1953, Serial No. 395,722

Claims. (Cl. 200-1) Electric switches are known in which the actual contact or contacts of a movable contact carrying member is or are respectively resiliently movable with relation to the Contact carrying member, e. g. supported by a relatively thin, flexible tongue fixed to the said member and and deviating in the open position of the switch towards the fixed contact member or members of the device. Upon contact closure this tongue or corresponding means is clamped between a portion of the contact carrying member and the associate countercontact or -contacts and due to the reslience of the tongue a bouncing of the movable contact carrying member upon contact closure will not cause any detrimental contact vibrations since the movable contact or contacts are pressed against the countercontact or -contacts respectively by the spring force acting on them, irrespective of oscillating movements of the contact carrying member within certain limits. Of course a similar elimination of contact vibration is obtained also when the countercontact or -contacts are somewhat movable, as often is the case, for instance in contact spring assemblies for relays and similar devices, in which the stationary contact springs sometimes are movably supported on a supporting stud or the like.

In most switching devices there is a predetermined minimum distance to be maintained between the movable and xed contacts in the open position and this contact distance in turn normally determines the utilization of the available space. When means of the described kind for eliminating contact vibrations are provided in known switching devices, however, additional space must be reserved for the said means, since the height of the contacts above the level of the contact carrying member in the open position must also include the length of relative movement between the contacts and the contact carrying member. A further result of this is that the required length of motion of the movable contact carrying member will be correspondingly increased.

The object of the present invention is to provide a switching device having means for eliminating contact vibrations operating according to the general principle outlined above but arranged in such a way that no appreciable increase of the required space or length of operating movement is caused thereby.

According to the invention the contact carrying device and means for eliminating contact vibrations are kept away by an operating member when they are in positions where they are not in contact with their associate countercontact member or members respectively.

An embodiment of a switching device according to the invention is hereinafter described by way of example with reference to the accompanying drawing in which:

Figure 1 shows a Contact spring forming part of a switching device according to the invention in side view;

Figure 2 shows the same contact spring in plan view;

.Figure 3 shows a Contact spring assembly as an eX- ample of a switching device according to the invention in elevation, having movable contact springs as shown in Figures 1 and 2; and

Figure 4 shows the same contact spring assembly in top view.

The movable contact spring shown in Figures 1 and 2 consists of a contact carrying member in the shape of a leaf spring 1 and a conductive, flexible tongue 2, which may be welded or riveted to the spring 1. The tongue 2 is slitted in its longitudinal direction so that two separately resilient portions having twin contacts 3 thereon are formed. It is also possible to make the flexible tongue 2 of contact material, such as silver or other suitable material, so that special contact bodies or points may be dispensed with. The tongue 2 is preferably materially thinner than the spring 1 and it is attached to the latter, at its one end only, a suitable distance from the end of the spring 1, so that the extreme portion of the latter forms a backstop or support for the tongue adjacent to its contact portion in operated position as will be more closely described below. The tongue 2 is pretensioned so as to tend to flex out from the spring 1 as shown in Figure 1.

The contact spring assembly illustrated in Figures 3 and 4 comprises two movable Contact springs 4 and 5, of the type described above with reference to Figures 1 and 2, and two stationary contact springs 6 and 7 carrying countercontacts for cooperation with the contacts of the movable contact springs 4 and 5 respectively. The movable contact springs are controlled by an operating member 8 which is vertically slidable inasmuch as it is slidably guided at its lower end in an aperture in a guiding strip 9 and at its upper end is engaged by a combined pressing and guiding spring 10, which spring has an aperture in which the top portion of member 8 fits. The stationary contact springs rest against supporting surfaces on a supporting stud 11, whereby they have their contact ends located on predetermined levels. All the contact springs are insulated from each other by means of insulating spacers 13 and the contact spring assembly is clamped between a washer 14 and a base plate 12 by means of screws 15.

The contact spring assembly shown contains one break contact function formed by springs 4 and 6 and one make Contact function formed by springs 5 and 7. The springs 4 and 5 are both pretensioned so as to tend to move their contact ends towards the corresponding countercontacts on the stationary springs 6 and 7 respectively and, when out of engagement with the operating member 8, to abut with their contacts 3 against the associated countercontacts on the stationary springs with a predetermined contact pressure.

The tongue 2 is then pressed against the end portion of its associate movable Contact spring 4 or 5 respectively. ln order that the tongue 2 may be completely flattened on the surface of the associate movable spring it will be understood, that its spring tension must be so chosen that the pressure required for pressing it against the underlying spring is at most equal to and preferably less than the contact pressure caused by the pretension of the associate movable Contact spring. The operating member 8 is provided with teeth 16 and 17 for the actuation of the movable contact springs 4 and 5 respectively. These teeth have lateral surfaces for the engagement with the ends of the movable contact springs. Thus in non-operated condition the operating member is kept in its lower position by the pressing spring 1t), whereby the movable contact spring 5 is kept apart from its associate stationary contact spring 7 by the tooth 17, which engages the surface of the tongue 2 so that the latter at the same time is pressed against the end portion of spring 5. As already mentioned springs 5 and 7 form together a make contact function. Springs 4 and 6 which form a breal; contact function, are in the shown rest condition in contact with each other. The tooth 16 then being out of engagement with spring 4 and its associate tongue 2.

When the switching device is operated the operating member 8 is displaced upwardly, for example by means of a relay armature or the like acting on the lower end of the operating member 8. The movable spring will then be permitted to move through its spring tension towards the stationary spring 7, and the operating member 8 is displaced by a distance great enough to ensure that the tooth 17 comes out of engagement with spring 5 so that the contacts of the two springs are pressed together and these springs will take up the same position relative each other as springs 4 and 6 in the shown non-operated condition. At the moment that the contacts of the movable contact spring 5 hit countercontacts of the stationary contact spring 7 either spring 5 may bounce back again or spring 7 may be pushed up or both such movement may occur, so that a tendency of contact vibrations arises. Due to the upwardly directed spring tension of the tongue 2, however, the latter will ensure that the contacts are closed even though the springs 5 and 7 vibrate or bounce in relation to each other.

On the upward movement of the `operating member 8 the tooth 16 engages the surface of the tongue 2 and forces the end `of the movable contact spring 4 upwards so that the contacts on springs 4 and 6 are separated from each other. When the operating member S has reached its highest position the springs 4 and 6 have the same relative positions as springs 5 and 7 in the nonoperated condition of the device.

When the device is restored to normal the reverse operation will take place, the contacts on springs 5 and 7 being again separated by the force transmitted from the pressing spring 10 by the tooth 17 on the operating member 8 and the contacts on springs 5 and 7 being again closed through the inherent spring tension of the movable contact spring 4. At the contact closure any tendency of contact vibrations is suppressed by the tongue 2 on the contact spring 4 in the same way as described above in connection with springs 5 and 7 during the operation of the device.

lt will be appreciated that due to the fact that the movable contact springs are pre-tensioned so as to effect contact closure by their own spring tension and the operating member acts according to the release principle and engages the movable springs by the intermediary yof the flexible contact tongues the latter will in open position of the contacts be pressed against the respective underlying spring and thereby cause no appreciable increase of space or operating movement but will still be released at the very moment of contact closure so as to absorb vibrations of the contact springs. It will be understood that the action of the tongues 2 will be most effective when the movement of the operating member is more rapid than the contact closure movement of the movable contact springs imparted to them by their own spring tension.

We claim:

l. A switching device comprising: a base structure; a stationary contact member on said base structure; a rst cantilever spring supported on said base structure and extending from its supported section with its free end in proximity to said stationary contact member; a second cantilever contact spring attached at one end to said first cantilever with its other free end adjacent said stationary contact member; said first cantilever spring being pretensioned so that it is biased towards said stationary contact member to normally press said second cantilever spring against the stationary contact, and said second cantilever contact spring being pretensioned to flex away from said lfirst spring towards said stationary contact member when unrestrained so that it tends to maintain contact therewith when the first spring is spaced therefrom; and operating means to displace said first and second cantilever springs away from said stationary contact member to disrupt contact therebetween.

2. An electric switching device as defined in claim l wherein said second spring is of contact material.

3. An electric switching device as defined in claim 2 wherein said second spring is made of silver.

4. An electric switching device as defined in claim l wherein said second spring is provided with contact points made of contact material.

5. A switching device comprising: a base structure; a stationary contact member on said base structure; a first cantilever leaf spring supported at one end on said base structure with its other free end in proximity to said stationary contact member; a second cantilever leaf spring attached at one end to said first cantilever spring on the side thereof disposed towards said stationary contact member with its other end adjacent said stationary contact member; said second cantilever leaf spring being pretensioned to flex away from said first cantilever leaf spring towards said stationary contact member when unrestrained so that it tends to maintain contact with said stationary contact; and operating means to displace said first and second movable contact members away from said stationary contact to disrupt contact therebetween.

6. An electric switching device as defined in claim 5 wherein said second leaf spring is provided with a slot which divides into two portions movable with relation to each other for forming twin contacts.

7. A switching device comprising: a stationary contact member; a first cantilever supported leaf spring having its free end in proximity to said stationary contact member; a second cantilever leaf spring attached at one end to said first cantilever spring on the side thereof disposed towards the stationary contact member, with its other free end adjacent said stationary contact member; said first cantilever spring being pretensioned so that it is biased towards the stationary contact member to normally press said second cantilever spring against said contact member, and said second cantilever spring being pretensioned to flex away from said first cantilever spring towards said stationary contact member when unrestrained so that it tends to maintain engagement with said stationary contact when the first spring is spaced therefrom; and an operating means for engaging the free end of said second cantilever spring to displace said first and second cantilever springs from said stationary contact member to disrupt contact therebetween, said operating member operating on the first cantilever spring through said second cantilever spring.

8. A switching device comprising: a base structure; a stationary contact member on said base structure; a first cantilever leaf spring supported at one end on said base structure with its other free end in proximity to said stationary contact member; a second cantilever leaf spring attached at one end to said first cantilever spring on the side thereof disposed towards the stationary contact member with its other free end adjacent said stationary contact member; said first cantilever spring being pretensioned so that it is biased towards said stationary contact member to normally press said second cantilever spring against it and said second cantilever spring being pretensioned to flex away from said first cantilever spring towards said stationary contact member when unrestrained with a force less than the pressure exerted on it by said first cantilever spring; and operating means to displace said first and second movable leaf springs away from said stationary contact to disrupt contact between it and said second spring.

9. A switching device comprising: a base structure; a relatively rigid cantilever leaf spring supported on said base structure with a relatively stationary contact part adjacent its free end; a second cantilever leaf spring supported at one end on said base structure in opposed relation to said first spring with its other free end in proximity to said stationary contact part; a third cantilever leaf spring lattached at one end to said second cantilever spring on the side thereof disposed towards the rst spring with its other free end adjacent to said stationary contact member, said second leaf spring being pretensioned so that it is biased towards said first spring to normally press said third cantilever spring against said stationary Contact part, and said third cantilever spring being pretensioned to iiex away from said second cantilever spring towards said stationary contact part when unrestrained with a force less than the pressure exerted on it by the said rst cantilever spring; and an operating member for engaging the free end of said third cantilever spring to move said third and second cantilever springs away from said stationary contact part to disrupt contact therebetween, with said operating means actuating the second cantilever spring through said third cantilever spring.

10. An electric switch comprising: a base structure; a first relatively xed contact member on said base structure; a carrying member supported on said base structure for movement towards and away from said first Contact member; a second contact member supported on said carrying member in engageable relation to said irst contact member with said second contact member movable relative to the carrying member, and said carrying member having a stop surface thereon engageable by said second contact member; said carrying member being biased to press said second contact member against said iirst contact member when said stop surface engages the second contact member, and said second contact member being biased to tend to move out of engagement with said stop surface on the carrying member towards said first contact member, with the bias on said second contact member being of less force than the bias on said carrying member; and operating means for moving said second contact member away from said rst contact member to disrupt contact therebetween.

References Cited in the tile of this patent UNITED STATES PATENTS 1,879,349 Lederer Sept. 27, 1932 2,115,836 Zupa May 3, 1938 2,178,151 Wagar Oct. 31, 1939 2,199,508 Nace May 7, 1940 2,271,813 Clayton Feb. 3, 1942 2,416,736 Buckley Mar, 4, 1947 2,472,709 Knapp I une 7, 1949 2,519,731 Aust Aug. 22, 1950 2,616,993 Koehler Nov. 4, 1952 FOREIGN PATENTS 603,150 Germany Sept. 24, 1934 OTHER REFERENCES Russell et aL: The Vibration of Electrical Contacts, AIEE Technical Paper 44-69, December 1943, 8 pages. 

